plane/3d object depth of field problem
If you want deeper focus you need a higher number for the f-stop.
Or you can render the foreground image and deal with the background and it's sharpness through compositing.
How to blur background image.?
How to Blur a Video Background in blender?
An alternative would be to work at a larger scale, so that the model won't be as close to the camera, and the focus won't be as critical.
Depth of Field F-stop not doing anything?
A different solution also is to work with a much smaller sensor, so that you work with even smaller lens size to achieve the same Field of View, and gain a bit of depth of field.
How do I set focus range?